David Cameron and Nick Clegg are planning to issue a prompt response next week to a report on the future of the government's NHS reforms amid fears that voters will not tolerate any further delays.

As a poll shows deep unease among Liberal Democrat voters about the original reform plans, Whitehall sources indicated that the prime minister and his deputy are to embark on intensive negotiations in the next few days before ending the "pause" on NHS plans next week.

Cameron and Clegg are being given updates by Professor Steve Field, the GP who was called in by Downing Street to oversee the "listening exercise" before his report is published. The briefings by Field, who chairs the NHS Future Forum, have allowed Cameron and Clegg to adjust their thinking and to hammer out agreement on disputed areas between themselves.

It is understood that Cameron and Clegg plan to issue an agreed government position soon after publication. "We do not want a great gap between receiving the report and responding to it," a Whitehall source said. "The response will be quick. Once the government responds there will be unity.

"It is better to have it out now rather than drag this out. Real issues are being fought over by the prime minister and the deputy prime minister. But people's patience is running out. So once the report is published, there will be a unified voice."

Clegg will also brief Evan Harris, a former Lib Dem MP, and Lady Williams of Crosby, a former member of the Gang of Four, who led the vote against the NHS reforms at the party's spring conference in March. The original reforms would have given 65% of the NHS budget to GP-led consortiums and would allow for greater competition in provision of services.

Clegg made clear last month that the controversial health regulator Monitor cannot be allowed to "push competition". He also said that the membership of the GP-led consortiums will be opened up and no doctors will be forced to join.

The pressure on Clegg is highlighted on Monday by a poll which shows that one third of those who voted Lib Dem in 2010 said they would switch to Labour if the reforms are left unchanged. It found that 34% of those who voted Lib Dem in the general election would be less likely to vote Lib Dem again if the bill remained unchanged; 32% were more likely to vote Labour. A key Lib Dem demand to put councillors on commissioning bodies is opposed by their own supporters by 50% to 22%.

The poll by PoliticsHome.com, in conjunction with the YouGov@Cambridge thinktank, found voters thought the Tory party was not to be trusted with the health service: 59%agreed that "deep down, the Conservatives want to fully privatise the NHS".

Cameron will today attempt to reassure anxious voters that the NHS remains safe in his hands when he outlines five guarantees on the health service. These are: not endangering universal coverage; improving efficient and integrated care; ensuring that waiting times are "kept low"; an increase in NHS spending; and no "selloff" of the NHS.

But he will also argue that failure to reform the NHS will threaten its core principle: that it is free at the point of delivery. He will say: "We have to change the NHS to avoid a crisis tomorrow too. This is what will happen if we don't: more over-stretch, more over-crowding, the NHS buckling under the pressure of an ageing population and the rising cost of treatments."

However, Ed Miliband, the Labour leader, will say: "David Cameron is the first prime minister in history to be forced to set out five pledges to protect the NHS from his own policies. Yet, he has already broken two of those pledges.

"The number of people waiting 18 weeks for treatment has gone up. He has not protected the health service budget. He has spent a year mismanaging the NHS. The consequences are chaos, confusion and damage to patient care.

"Hundreds of millions of pounds, which should have been used for patient care, are being wasted on handing redundancy notices to staff from PCTs who may now have to be rehired."

The PoliticsHome poll found that overall there was support for the need for reforms. It found that 71% of respondents supported the assertion: "The way in which the NHS spends its money needs to be reformed, as increased life expectancy and new drugs mean it is always becoming more expensive to run." The poll found that 6% opposed the assertion. Not making any changes to how health services are commissioned was opposed by 37% to 20%.

Commissioning by GPs was supported 38% to 33%. Making commissioning more locally accountable was supported 73% to 5%, rising to 85% to 4% among over-60s.

The idea of a competition regulator for NHS services was narrowly supported 33% to 29%, but the policy of "any willing provider" is opposed by 38% to 31% – a clear partisan split; Labour voters opposed it by 19% to 59%.

While large numbers still believe the Tories want to privatise the NHS, 38% to 26% believe Conservatives do want NHS free at the point use and 45% to 23% think any NHS reforms the Conservatives make are aimed at helping business not patients.

PoliticsHome.com, in conjunction with the YouGov@Cambridge thinktank, polled 2,242 adults between 31 May and 1 June 2011